Heretofore, as a rotary body fixing device for use in detachably fixing a rotary bodes such as, for example, a pulley or a gear to a shaft, there has been known a rotary body fixing device of a structure in which opposed outer and inner peripheral surfaces of concentric inner and outer rings, respectively, are formed as a pair of tapered surfaces so that the spacing between the paired tapered surfaces is wider toward both sides from an axially central part, a pair of tapered rings are inserted into the space between both tapered surfaces axially from both sides, and both tapered rings are pulled toward each other with a large number of clamping bolts, thereby causing the inner peripheral surface of the inner ring to expand and come into pressure contact with the said shaft and causing the outer peripheral surface of the outer ring to expand and come into pressure contact with the inner peripheral surface of the boss hole formed in the rotary body, to clamp the shaft and the boss.
In the rotary body fixing device of the above structure, the angle of each tapered surface is designed to be small in order to increase the clamping force and therefore even after the clamping bolts have been loosened for removing the rotary body from the shaft, both tapered rings remain self-locked and fixed between the inner and outer rings by virtue of a frictional force.
To avoid such inconvenience, the conventional rotary body fixing device in question is usually provided with a structure for extracting the tapered rings which are firmly wedged into the space between the inner and outer rings. FIGS. 9-12 show an example of a conventional rotary body fixing device having the said structure, of which FIG. 9 is a side view thereof and FIG. 10 is a sectional view as seen in the arrowed direction 10--10 in FIG. 9.
As shown in these figures, a rotcary body fixing device 11 is provided with an elastically deformable inner ring 12 to be mounted on a shaft and an elastically deformable outer ring 13 to be fitted in a boss hole formed in the rotary body. The opposed confronting surfaces of the inner ring 12 and the outer ring 12 are formed as tapered surfaces so that the spacing between both surfaces is wider toward both outer sides from an axially central part. A pair of tapered rings 14 and 15 are inserted axially from both sides into the space formed between both such tapered surfaces. Clamping bolts 16 are inserted through clamping bolt holes 14A formed in one tapered ring 14 and are brought into engagement with tapped holes 15A formed in the other tapered ring 15 to clamp both tapered rings.
Annular grooves 12A and 13A of an equal width are formed in axially central portions of the opposed surfaces of the inner ring 12 and the outer 13, respectively, and a spacer ring 17 is held between the annular grooves 12A and 13A. Holes 17A for passing the clamping bolts 16 therethrough are formed in the spacer ring 17.
On the other hand, extraction bolt holes 14B are formed at positions opposed to clamping bolt holes 14A in the tapered ring 14 radially with respect to the axis. Part of the inner peripheral surface of each extraction bolt hole 14B is formed with internal threads.
FIG. 11 shows a manner in which one tapered ring 14 wedged into the space between the inner ring 12 and the outer ring 13 is extracted after removal of the clamping bolts 16. Extraction bolts 18 are threadedly engaged with the internal threads of the extraction bolt holes 14B and their tip ends are brought into abutment against the spacer ring 17. As the extraction bolts 18 are turned, the tapered ring 14 now engaged with the extraction bolts 18 is extracted leftwardly from between the inner ring 12 and the outer ring 13 because the advance of the extraction bolts 18 is inhibited by the spacer ring 17.
FIG. 12 is a sectional view as seen in the arrowed direction 12--12 in FIG. 9, with the tapered ring 14 removed, showing in what manner the other tapered ring 15 is extracted. Tapped holes 17B for threaded engagement with the extraction bolts 18 are formed in the spacer ring 17 at positions each between adjacent holes 17A. As the extraction bolts 18 are screwed into the tapped holes 17B after extraction of one tapered ring 14, the tip ends of the extraction bolts 18 abut the end faces of the other tapered ring 15, whereby the tapered ring 15 can be pushed out rightwardly in FIGS. 11 and 12 from between the inner ring 12 and the outer ring 13.
In the conventional rotary body fixing device constructed as above there has been a problem such that the spacer ring held between the annular grooves of the inner and outer rings, respectively, shakes and generates noise during rotation of the rotary body fixing device.
Besides, since the spacer ring requires a threading work in plural positions, the number of manufacturing steps is increased. Moreover, the operation for inserting the spacer ring into the space between the inner and outer rings requires the use of a special assembling jig for elastic deformation of both rings and for press-fitting the spacer ring into an axially central part of the space between both rings. This causes an increase in the manufacturing cost of the rotary body fixing device.
Further, when the rotary body fixed onto the shaft by the rotary body fixing device is to be removed, the clamping bolts are loosened. However, as mentioned above, the paired tapered rings are fixed in a self-lock condition between the inner and outer rings. Therefore, it is required to first insert the extraction bolts threadedly into the extraction bolt holes formed in one tapered ring and rotate them to extract the one tapered ring, thereafter insert the same extraction bolts into the tapped holes formed in the spacer and rotate them to push out the other tapered ring. Thus, much labor and time are required for detaching the rotary body from the shaft.